1. Field of the Invention
The present invention relates to an input module of a portable electronic device and more particularly to an input module of a portable electronic device being durable and resistant to bending deformation.
2. Description of the Related Art
Technological progress has created many portable electronic devices to facilitate electronic operations of users. When it comes to the cursor control of notebook computers or tablet personal computers (PC), mice of desktop computers are technically feasible while they are inconvenient as far as portability is concerned. Such inconvenience opens a door for input modules mounted on portable electronic devices. With reference to FIG. 8A, users can control cursor positions by moving their fingers on the input module 60. To completely replace the function of a mouse, the input module 60 further has a physical switch serving for users to press and simulating the functions of the left button and the right button of a regular mouse.
With reference to FIGS. 9 and 10, a conventional input module 60 of a portable electronic device has a sensing board 61, a cover lens 62, a physical switch 63 and a side-fixing plate 64.
The cover lens 62 is mounted on a top surface of the sensing board 61 for users' fingers to touch.
The physical switch 63 is mounted on and electrically connected to a bottom surface of the sensing board 61, and is adjacent to a central position of one of two relatively long sides of the sensing board 61.
The side-fixing plate 64 is shorter than the sensing board 61 in width and is mounted on the other relatively long side of the sensing board 61. One side of the side-fixing plate 64 protrudes beyond one of the two relatively long sides of the sensing board 61. The side-fixing plate 64 is screwed on an assembly portion 51 on the front of the portable electronic device.
With reference to FIG. 11, to let the physical switch 63 of the input module 60 be activated when the cover lens 62 is pressed down, the assembly portion 51 has a protrusion 52 to correspond to the physical switch 63. When the cover lens 62 is pressed, the physical switch 63 abuts against the protrusion 52 and is activated. Meanwhile, the input module 60 detects a force application point exerted by a user on a left half region or a right half region of the cover lens 62 with respect to the physical switch 63 to correspond to input signals of a left button and a right button and implement the control functions of the left button and right button of a mouse.
As mentioned, the foregoing input module 60 can identify users' left-button or right-button operations with single physical switch 63. With reference to FIG. 8B, one of two relatively long sides of the input module 60 is fastened on the assembly portion 51 through the side-fixing plate 64, and users oftentimes press corners indicated by a letter ‘F’ and being adjacent to the other relatively long side and two relatively short sides of the input module 60 to input through the left button or the right button. According to the torque equation, a lever arm D1 is determined by a distance between the pressed point ‘F’ and a fixed point (fulcrum), and a torque is obtained by a product of the lever arm and a force. The longer the lever arm is, the higher the torque and the bending stress are. After having been operated for a long time, the input module is prone to permanent deformation and gaps formed between the assembly portion 51 and the portable electronic device easily store dirt and filth that is hard to be cleaned up.